A magnet generator type ignition device is extensively adopted for such internal combustion engines as, for example, for chain saws and special vehicles. Its purpose is to obtain an ignition current source of high voltage instead of employing a battery. A low voltage current generated the magnet generator is taken, is increased in voltage by an ignition coil and is fed to the spark plug.
Now, in the constant operation of such internal combustion engine as of a chain saw, the ignition time is set near 30 degrees before the top dead center so that the combustion efficiency of the gaseous mixture may be at its maximum. Therefore, when the rotating speed of the internal combustion engine is low as at the time of starting the engine, if the ignition is made at the same ignition time as is mentioned above, the internal combustion engine may rotate reversely, making the starting difficult. That is to say, there have been problems that, when the rotating speed of the engine is low, if the ignition occurs near 30 degrees before the top dead center, the piston will fall before it reaches the top dead center, a force will act to push back the crank and a force to reversely rotate the engine will be created.